Azimuthal angle dependence of the charge imbalance from charge conservation effects

TL;DR

This paper investigates how charge conservation effects influence charge-dependent correlations in heavy-ion collisions, suggesting that observed signals attributed to the chiral magnetic effect may instead be explained by background effects like resonance decays and local charge conservation.

Contribution

It introduces a new observable based on third order harmonic flow to distinguish background effects from genuine signals of the chiral magnetic effect.

Findings

Preliminary STAR data can be explained by background effects.

A new observable can help disentangle background effects from the chiral magnetic effect.

Hydrodynamic model results support background explanations.

Abstract

The experimental search for the chiral magnetic effect in heavy-ion collisions is based on charge dependent correlations between emitted particles. Recently, a sensitive observable comparing event-by-event distributions of the charge splitting projected on the directions along and perpendicular to the direction of the elliptic flow has been proposed. The results of a 3+1-dimensional hydrodynamic model show that the preliminary experimental data of the STAR Collaboration can be explained as due to background effects, such as resonance decays and local charge conservation in the particle production. A related observable based on the third order harmonic flow is proposed to further investigate such background effects in charge dependent correlations.